Micro-computer terminals and printers are frequently used for the electronic transacting of consumer payments in a retail store using credit cards. In general, the retailer inputs the consumer's payment account number into the terminal, typically a device having a keypad and a magnetic card reader, and the terminal approves the transaction by communicating with a remote host computer. Upon approval, the micro-computer directs the printer connected thereto to create a receipt, which is signed by the consumer as a written record of consent to pay the retailer. The entire process takes about two minutes. To save time, some micro-computer terminals print a portion of the receipt, referred to as the print header, concurrently while requesting an approval. After an approval is obtained, the remainder of the receipt, referred to as the print trailer, is printed.
In order to meet the increased demand for credit card transaction processing during peak times while keeping costs low, a number of micro-computer terminals may be connected to a single printer. Because the printed data takes only a short time to transmit, a number of transactions can be printed in without significant delay on a single printer if they are transmitted in sequence. The problem is that two or more micro-computer terminals may attempt to transmit data to a printer simultaneously, thereby causing potential confusion by the printer regarding the data; or one micro-computer terminal may be in the process of transmitting data when a second micro-computer terminal initiates a data transfer, again potentially causing a printer malfunction.
It would be desirable to have an apparatus that would automatically direct micro-computer terminal data traffic to a single printer so as to avert this confusion. It would be desirable for such an apparatus to be conveniently added to an existing micro-computer terminal and printer system without requiring modification to either the micro-computer terminal or the printer.